I have a small sign next to my doorbell on the front of my house that says "No Solicitors". Quite often I see people walking down the street, going door to door. They get to my house, walk up to the front door, and (MOST of the time) they turn around and walk away. When I invite friends to come over to my house, they walk up to my door, and ring the doorbell. How does this work? It is simple challenge/response. (My friends don't come over to the house, see the sign and then leave)
No, it is not chanllenge/response. You do not present challange. And you do not require response. If you remove the sign, and install device on your doorbell that will when solicitors and friends press the doorbell (or before pressing it) sound "if you are not solicitor say kazuba", and then they respond with "kazuba" in order to be allowed to proceed, than it would be C/R system. You present challenge (trivial challenge, but still challenge), and await for response.
The system you have in place is based on assumption that most people are polite. Computer equivalent would be placing "no spam" in your mail server's greeting. It wouldn't be very effective, since there is no such thing as polite spammers. Solicitors that walk away from your door when seeing the sign have shown an act of politeness no matter what you think about solicitors in general.
-- Aleksandar Milivojevic <amilivojevic@xxxxxx> Pollard Banknote Limited Systems Administrator 1499 Buffalo Place Tel: (204) 474-2323 ext 276 Winnipeg, MB R3T 1L7
